Swimming in the Tidal Thames

Swimming in the tidal Thames is dangerous. It puts the lives of those who choose to dive in on the line, but also exposes boats, passengers and crews to unacceptable risk and disruption.

Every year the Royal National Lifeboat Institution, Metropolitan Police and Port of London Authority deal with tragic drownings. Most years more than 30 swimmers get into difficulty in the river.

Danger for swimmers:

Powerful tides, running at around five miles an hour, will overpower even the strongest swimmers

Eddies and undertows - caused by the uneven river bed, bridge pillars, piers and moored vessels – will suck swimmers under in seconds and keep them below the surface for days. No safety precautions can counter these lethal currents – surviving them is a simply matter of luck.

Bitingly cold river water will cripple the most accomplished swimmers and cause involuntary breathing spasms – known as a ‘gasp reflex’ – when a person is temporarily submerged.

39 million cubic metres of raw sewage finds its way into the Thames every year. These spillages occur when heavy rainfall overwhelms the capital’s Victorian sewage system.

Danger for other river users:

The tidal Thames is the UK’s busiest inland waterway and second biggest port. Passenger boats, some carrying more than 600 people, can be forced to take sudden avoiding action if a swimmer appears in their path, putting everybody aboard at risk of collision with bridges, piers or other vessels. Swimming is also as disruptive as hiking on a motorway, airport runway or railway line.

The Thames accommodates 20,000 ship movements, 200,000 leisure craft trips and 50 sporting events each year. It’s a busy river that can’t accommodate swimmers putting their own safety - and the safety of others - at risk.